Chemical process



Patented Oct. 3, 1939 UNITED STATE CHEMICAL PROCESS Joseph Barrel Shipp,

to E. I. du Pont de Nemours & Company,

Wilmington, Del., assignor Wilmington, Del., a corporation of DelawareNo Drawing. Application April 22, 1936, Serial No. 75,868

20 Claims.

This invention relates to the treatment of textiles, particularlycellulosic fibers, yarns and fabrics, with sulfuric acid to obtainparchmentizing effects; and more particularly to the treatment ,r, ofcotton fabrics with concentrated sulfuric acid containing an agent whichwill inhibit the tendering effect of the acid.

It is generally known that concentrated sulfuric acid is destructive totextile materials. nevertheless certain uses of sulfuric acids ontextiles are so advantageous that endeavors have been made to so treattextileswith sulfuric acid as to obtain the desired effects but to avoidthe undesirable effects. Thus there is a series of patents which dealwith the treatment of fabrics with sulfuric acid in connection with aseries of mercerization treatments.

This invention hasas an object the production of permanent finishes onfabrics. "A further ob-v ject is the production of permanent finishes onyarns, textiles, fabrics, paper and the like. A still further object isthe production of parchmentized effects on cellulosic fabrics. A stillfurther and particularly desirable object is the production of organdyfinishes on cotton fabrics. Other objects will appear hereinafter.

These objects are accomplished by the following invention wherein thefabric to be treated is passed continuously through the parchmentizingbath consisting of especially inhibited strong sulfuric acid, thencethrough rolls or other means for squeezing out the excess parchmentizingreagent, then through washing and neutralizing baths, and finally over acalender or other drying means. In this procedure the speed and time ofimmersion of the goods in the parchmentizing bath are adjusted with dueregard to the result desired and to the end that the goods aretransparentized to the desired degree and that the parchmentizingreagent is washed out before the goods are tendered to an objectionabledegree. The novel'feature of this process is the parchmentizing reagentwhich consists of strong sulfuric acid of at least 65% concentration andpreferably from 80% to about 98%, having dissolved therein an agentcapable of inhibiting or at least greatly retarding the normal degradingaction of strong sulfuric acid upon cellulose. This agent is termed thecellulose degradation inhibitor. In 0 the claims the percentagecomposition of the acid refers to the composition of the acid prior tothe introduction of the inhibitor.

Gil

It is known that strong sulfuric acid has a marked degrading ordisintegrating effect on cellulose fibers, which in the case of acid ofmoderate strength quickly produces a marked tendering of the fiber andin the case of concentrated sulfuricacid such as 96%, results in almostinstantaneous and complete destruction of the fiber.

Now it has been discovered that the degrading effect of the acid on thecellulose may be inhibited or retarded by dissolving in the acid certainagents which are termed inhibitors of cellulose degradation. Aninhibitor suitable for use inthis invention may be known by the factthat it meets the following tendering resistance test. For this test,parts of the material to be tested is dissolved in 100 pts. of 96%sulfuric acid, the solution is brought to 20 C. and a sample of cottonvoile of known tensile strength is immersed therein for aperiod of 30seconds after which the sample is withdrawn from the acid, washed toneutrality, and dried by ironing. The sample is now examined forparchmentizing and tested for loss or gain of tensile strength. If thesample is found to be parchmentized and to have increased in tensilestrength or to have lost less than of its original tensile strength, itis considered that the agent tested is a satisfactory inhibitor ofdegradation for use in this invention.

If a cotton fabric is immersed in 96% sulfuric acid at room temperature,removed immediately and rinsed veryquickly with a large volume of water,the fabric is disintegrated and destroyed. However, if as much as 25parts by weight of urea is first added to each 100 parts of acid, then afabric may be treated with this solution up to 60 seconds without beingappreciably tendered. If fabrics so treated are washed free of acid,using dilute alkali if desired, then ironed dry, a pleasant, stiff,springy finish is obtained. When this treatment is applied to cottonvoile or lawn, an organdy finish results. Not only is the cloth stiffand springy, but it is also more transparent than the original cloth.The effect is permanent to washing. Instead of urea, certain othermaterials may be used. These are listed below.

In carrying out the process in its preferred form, the agent is firstdissolved in concentrated sulfuric acid with cooling if'necessary toprevent decomposition. The sulfuric acid may be from about 65 andpreferably from 85 to over 100 per cent strength. From 10-30 parts byweight of agent per 100 parts of acid' is satisfactory. The, quantity ofagent, as well as the concentration of initial acid, may be variedsomewhat depending on the time the textile material is to be in contactwith the solution, and depending on the effect it is desired to produce.The parchmentlzing is slower and less pronounced with increasingquantities of inhibitor. The'time of contact of the textile materialwith the solution will ordifabric.

solution of one of these agents and sulfuric acid,-

Lowering the temperature retards the parchmentizing effect. It will beseen that the degree of parchmentizing obtained can be varied at willover very wide limits by varying (1) the amount of inhibitor in theacid, (2) the amount of water in the acid, (3) the temperature of thesolution, and (4) the time of contact of the cellulosic material withthe'solution.

The textile material, e. g., cotton fabric, is

passed through the acid solution and then into water to remove the acid,then dried by ironing or calendering, or on a tenter frame which exertsa shearing action to minimize sticking together of the warp and fillingthreads at points of contact. The washing may be facilitated by usingwater first, followed by a dilute solution of a base such as ammoniumhydroxide or sodium hydroxide. It is important that the greater part ofthe acid be washed out very rapidly in order to avoid local heatingwhich would destroy the If a cellulosic material is treated in a andthen slowly immersed in water, the cellulosic material will be tenderedor totally destroyed.

A novel fabric has been produced by treating cotton web, produced on acarding machine, with these inhibited sulfuric acid solutions. Thefibers are stuck togeth'er at each point of contact, resulting in astrong sheet. This process affords a possibility of omitting the stepsof spinning and weaving in the preparation of fabrics suitable for a.variety of purposes. 3

Instead of using a. single agent in the solution two or more may be usedfrom the same or from different groups, or certain other agents may beadded to give enhanced effects. A solution containing an amide and anether, or an amide and an alcohol, or an amide and an amine, will givevery satisfatory parchmentizing effects with practically no tendering ofthe cellulosic material. The use of additional agents also affords meansof varying the effects obtained. Thus, an amide. alone or an amide andan amine, or an amide and an alcohol, produce transparent organdyfinishes, whereas an amide and a relatively large proportion of an etherproduce an opaque parchmentized efi'ect. Also, some agents give a moretransparent finish than others. Thus, acetanilide anddecamethylenediamine give opaque finishes.

If only limited areas of a fabric are treated by this process, a patterneffect may be obtained. Alternatively, certain areas of the fabric maybe immunized against the sulfuric acid treatment and the fabric may thenbe treated over its entire surface with the acid to obtain patterneffects. Thus, areas printed with paraflin are not affected by the acidtreatment, and this affords a means of immunizing against sulfuric acid.

Unfinished cotton fabrics can be treated by this process without anyprevious or subsequent mercerization and will yield, by a singletreatment, a transparent organdy finish. The advanmercerization step isnot necessary to produce a good permanent organdy finish.

Instead of washing the fabrics in water after the acid treatment theymay first be washed in aqueous sulfuric acid (25 to 50 per cent H2804)and then washed in .water. This reduces the ,1 cost of the treatment,since the dilute sulfuric acid produced, may be utilized in otheroperations.

While the use of inhibited sulfuric acid is of particular interest andvalue on cotton fabrics, for producing organdy efiects, linen, and'rayon may also be treatedby this processwith advantageous results. Inthis manner an organdy finish can be obtained on rayon voiles.

Fabrics or yarns treated by this process may be stretched during orafter the acid treatment. The-tenacity of cellulosic yarns is increased-by stretching duringor after the acid treatment.

In the above the invention has been considered in considerable detail,the principles of the invention being set forth minutely. The followingexamples still further illustrate the invention, but are purelyillustrative and not limitative.

Example 1 of urea, the acid being cooled during the addition of theurea. After the urea was completely dissolved, the solution was cooledto 20 C. A 68/76 unfinished cotton voile fabric was immersed in thesolutionfor 30 seconds, removed, drained for a few seconds, then plungedinto water at room temperature. After washing thoroughly in water it wasrinsed in a. 3 per cent solution of ammonium hydroxide, rinsed in waterand dried by ironing. A stiff, springy finish of the type commonlycalled transparent organdy was obtained. The fabric was boiled for onehour in 0.5 per cent soap solution, rinsed and dried. The finish was notappreciably affected by this laundering.

If it is desired, the fabric may be mercerized with caustic in the usualway either before or after, or both before and after, the above acidtreatment. 'Alternatively, two acid treatments of the type indicated maybe given the fabric with mercerization between the two acid treatments.

Example 2 A 68/76 unfinished cotton voile fabric was immersed forseconds in a solution of 20 g. thi- 'ourea in 100 g. 96% sulfuric acid,removed,

drained for a few seconds, rinsed in water, then in dilute ammoniumhydroxide, and again in water, and dried by ironing. A transparentorgandy finish was obtained which was permanent I r to washing.

Example 3 Example 4 I A 68/76 unfinished cotton voile fabric was treatedfor 20 seconds with a solution of 20 g. of acetamide in 100 g. 96%sulfuric acid. The fabric was then removed, drained-for a few seconds,washed with water, dilute ammonium hydroxide and water, and dried byironing. A transparent organdy finish was obtained. This finish Example5 A 68/76 unfinished cotton voile fabric was immersed for 20 seconds ina solution made by adding 20 g. oxamide to 100 g. 96% sulfuric acid. Theoxamide was only partially soluble in the acid. The fabric acquired apermanent transparent organdy finish but was slightly tendered;

Example 6 A 68/76 unfinished cotton voile fabric was treated for 20seconds-with a solution of 20 g.

acetanilide in 100 g. 96% sulfuric acid. An

. opaque organdy finish was obtained and the fabric was only veryslightly tendered by the treatment.

Example 7 A 68/76 unfinished cotton voile fabric was treated for 30seconds in a solution of 25 g. of diethyl ether in 100 g. of 96%sulfuric acid. After the fabric was washed and dried it possessed atransparentorgandy finish which was permanent to washing.

Exampletl An unfinished cotton voile fabric was treated for 10 secondswith a solution of 25 g. of ethyl alcohol in 100 g. 96% sulfuric acid,then washed in water, dilute ammonium hydroxide and water, and dried. Atransparent organdy finish was obtained which was permanent to washing.

Example 9 An unfinished cotton voile fabric was treated for 20 secondsin a solution of 25 g. of acetone in 100 g. 96% sulfuric acid, washedand dried. A permanent organdy finish was obtained.

Example 16 An unfinished cotton voile fabric was treated for 10 secondswith a solution containing 20 g. of guanidine carbonate in 100 g; 96%sulfuric acid. A pleasing permanent organdy finish was obtained.

Example 11 An unfinished cotton voile fabric was treated for 10 secondswith a solution containing 25 g. of phenyl hydrazine in 100 g. 96%sulfuric acid. A permanent organdy finish was obtained. The fabric wasslightly discolored.

Example 12 A 68/76 unfinished cotton voile fabric was treated for 10seconds ina solution of 20 g. of urea and 5 g. of diethyl ether in 100g. of 96% sulfuric acid. After the fabric was washed and dried, itpossessed a transparent organdy finish The tensile strength of thefabric was slightly greater than that of a fabric treated in a solutioncontaining only urea and sulfuric acid.

Example 13 A 68/76 unfinished cotton voile fabric was treated for 20seconds with a solution of 5 g. urea and 20 g. diethyl ether in 100 g.96% sulfuric acid. The acid was washed out with water and diluteammonium hydroxide and the fabric dried by ironing. An opaque organdyfinish was obtained, the treated fabric being stiff and springy but nomore transparent than the untreated fabric.

Example 14 A 68/76 unfinished cotton voilefabric was treated for 10seconds with a. solution of 20 g. urea and 5 g.-ethyl alcohol in 100 g.96% sulfuric acid. The fabric was washed free of acid anddried byironing. A transparent organdy finish of good tensile strength wasobtained.

Example 15 -A 68/76 unfinished cotton voile fabric was treated for 20seconds with a solution containing 5 g. of urea and 20 g. of ethylalcohol in 100 g.

96% sulfuric acid. A transparent organdy finish of high tensile strengthwas obtained.

Example 16 A 68/76 unfinished cotton voile fabric was treated for 20seconds with a solutioncontaining 25 g. of urea and 10 g. of water in100 g. 96%

sulphuric acid. After washing free of acid and ironing, a very stiff,transparent finish was obtained.

- Example 17 tained in Example 16. The fabric was not appreciablytendered.

v Example 18 A 68/76 unfinished cotton voile fabric was treated for 10seconds in a solution containing 25 g. of urea and 100 g. of 100 percent sulfuric acid. The fabric was-washed free of acid and dried byironing. A permanent transparent organdy finish was obtained.

Example 19 A viscose rayon crepe fabric was treated for 10 seconds witha solution containing 25 g. of urea in 100 g. 96% sulfuric acid. Thefabric was then washed free of acid and dried by ironing. The fabric wasstiffer and more transparent than the original fabric and was only veryslightly tendered.

This process can be applied to cotton, linen, viscose rayon or otherregenerated cellulose fabrics, threads or fibers. Although the chiefpurpose of the invention is to produce organdy finishes on cotton voilefabrics, permanent starched effects may be obtained on heavier fabrics.The invention is applicable to all types of cellulosic fabrics, but theresults are particularly desirable with textile materials such ascotton, viscose rayon, etc. The process is also applicable, as shown inthe following example, to the preparation of parchment paper.

' Example 20 An unsized'sulfite paper weighing 20 lbs. per 500 sheetsmeasuring 25" X38" was treated for 30 seconds in a solution of 20 g. ofurea dissolved in 100 g. of 96 sulfuric acid, then washed in water untilfree of acid. The paper was dried by ironing. As a result of thistreatment the paper was parchmentized. It was denser, harder, and moretransparent than the untreated paper. The treated paper has a muchgreater wet strength as revealed by a qualitative test in which bothtreated and untreated paper were wet and broken in the hand. Theresistance of the wet paper to rubbing was also greatly increased by thetreatment, The grease resistance of the treated and untreated paper wastested by placing the papers over white blotting paper and placing adrop of dyed turpentine on each in one test and a drop of a dyed cottonseed oil on each in a second test, and noting the time required for theoil to pass thru the paper. Both the turpentine and vegetable oilpenetrated the untreated paper instantly. -The turpentine penetrated thetreated paper in about one minute but the cotton seed oil had notpene-.- trated after a quarter of an hour. When written upon with inkthe treated paper gave a smooth even line whereas the untreated papergave an irregular line due to the blotting effect.

The sulfuric acid used in the parchmentizing reagent may vary from about80 to 100% H2804 or even higher and is preferably from about 90 to 98%H2804. When the inhibitor of cellulose degradation is an amide, forexample, urea, useful results may be obtained with acid concentrationsas low as 65% H2304. The concentrationof the inhibitor in the acid mayvary within rather wide limits depending on the inhibitor itself and onthe other conditions present. Under some conditions ratios as low as 5parts inhibitor to 100 parts acid may be useful and ratios as high as 35parts per 100 of acid may also be used provided the inhibitor issufficiently soluble in the acid. The process is most desirably operatedat normal temperature but the temperature may be varied somewhat aboveor below this point as desired.

In view of the number of variable factors, it is impossible to set forthin a patent application every possible combination of conditions whichmay be successfully operated. Given the requirement that a given qualityof finish is to be produced on a given fabric using a given inhibitor ofdegradation, it is essential that the variables be adjusted so as tocoordinate the reaction rate and the time of treatment so that a finishis obtained having the required properties. The various factorsaffecting speed of reaction are temperature, concentration of acid, andthe concentration of the inhibitor in the acid. The reaction rate may beincreased by increasing the temperature, or by varying the concentrationof the acid, or by decreasing'the concentration of the inhibitor in theacid. In general the speed of the parchmentizing reaction is increasedas the concentration of the acid approaches the point of maximumactivity which isabout 92%. Since the process is in general operatedcontinuously, it is obvious that the time of contact may be adjusted byvarying the speed of travel or by varying the length of travel in theparchmentizing bath.

When the situation is such that the time of contact may be varied atwill, the inhibitor to be used, for example, urea, is dissolved in theacid, the concentration of the acid and of the inhibitor in the acidbeing maintained at any desired point within the limits which have beenset and within the limit of solubility of the inhibitor in the acid, theparchmentizing bath is brought to the temperature at which it is desiredto operate, preferably around normal, and the fabric is passedcontinuously through this acid bath, the speed of travel being adjustedso that the degree of parchmentizing is satisfactory and that thereagent is washed out of the fabric before the fabric is tendered to anobjectionable degree. If desired, the optimum time of contact in theparchmentizing bath'may be readily determined merely by immersing asmall sample of the fabric in the parchmentizing reagent and varying thetime of immersion until the required effect is produced the reagent anddrying.

In the case where the time of treatment is limited, it may be necessaryto adjust the speed of after washing out reaction between the celluloseand the reagent so that the reaction is completed within the time limit.For example, when it is desired to complete rate so as to permita longertime of contact, this may be brought about by decreasing temperature orby varying the concentration of the acid or of the concentration of theinhibitor in the acid.

The process is not limited to any particular type of apparatus. Thenature of the reagents will necessitate apparatus which is not corrodedby concentrated sulfuric acid. With proper precautions, iron apparatusmay be satisfactory. The treatment of the fabric may consist in passingit through the acid solution containing the inhibitor at such a ratethat it will be thoroughly wet out by the acid, through squeeze rolls toremove excess acid, then into water at room temperature or below. It isessential that the water treatment should be such that the acid isdiluted very rapidly. This will avoid having local areas become hotenough to cause tendering of the fabric. Subsequently, the fabric shouldbe washed entirely free of acid using dilute alkali baths if desired,and then dried, either on a tenter frame or on hot rolls or calenders.The fabric may be given any other treatment desired for any particularfinish. Thus, it may be tenter sheared to break down the bond at theintersection of warp and filling yarns, thereby preventing the finishedorgandy from having a boardy feel. For the most part the treatment inaccordance with the present invention may be carried out in ordinarytextile plant equipment.

The fabric may be treated over its entire surface or only on certainareas, so as to give pattern effects. For this treatment, the acidcontaining the inhibitor could be printed on by ordinary printingmethods, using corrosion-resistant printing rolls. The treatment may becarried out by protecting certain areas with unreactive materials, suchas paraffin, and then treating the entire fabric. In this way, theprotected areas are not ailected, and a pattern effect may also beobtained.

The process of the present invention has been illustrated with the useof amides which are the preferred class of inhibitors or negativecatalysts of the present invention. In addtiion, the use of ethers,alcohols, ketones, amines and mixtures of ethers and amides have beenexemplified. As explained earlier in this specification, suitableinhibitors are soluble in 96% H2804 and may be known by the fact thatthey react positively in the tendering resistance test. Those inhibitorswhich are of low molecular weight are particularly desirable. Thus urea,thiourea, formamide and ethanol-formamide are excellent inhibitors.Acetamide and acetanilide are effective but not to the extent of thosejust mentioned. Oxamide and decamethylene-diamine formamide may be used,as well as the amides of formic acid with I forked chain amines whereinthe alkyl group ofthe amines contains at least six carbon atoms and aforked chain.

for example, at 85% and above thatthe advan- These low molecular weightamido compounds are defined bythe formula wherein R may be hydrogen, anamido (NHa) group or an alkyl group, R and R are hydrogen or hydrocarbonradicals and X may be oxygen, sulfur or an imino group. These compoundsare particularly effective 'when the compound contains 10% or more ofnitrogen. In addition to those already mentioned ,guanidine,diphenylguanidine, urea-formaldehyde resins and aminoguanidinebicarbonate are effective as inhibitors to varying extents.

In addition to the amido compounds,above discussed, which form perhapsthe most pre ferred class of inhibitors, amino compounds, e. g.decamethylene diamine, hexamethylene diamine, ethylene diamine,hexamethylene tetramine, 1, 3-diaminopropanol-2, dibutylamine, andtriethanolamine are effective as modifiers for concentrated sulfuricacid, i. e. sulfuric acid of at least 80% concentration.

Low molecular weight alcohols soluble in con.- centrated sulfuric acidhave also been found to be effective inhibitors for use with sulfuricacid of at least 80% concentration, including glycerol, methanol,ethanol, butanol, ethylene glycol, isopropanol and 1,3-diaminopropanol-2.

Similarly, ethers such as diethyl ether and diethylene glycol have beenfound useful in inhibiting the tendering of cellulosic materials bysulfuric acid.

Acetone, methyl ethyl ketone and dipropyl ketone are effective in theorder given, acetone being the preferred ketone.

In general the inhibitory effect decreases with increased molecularweight in a given series. The low molecular weight amides are moreeffective and are also more soluble, particularly the amides and amidoderivatives of monocarboxylic acids.

Materials which give viscous solutions are less desirable than thosewhich give limpid solutions, presumably because of the difference ofease of washing off the acid and also because of the slow wetting of thefabrics by these solutions.

While acids of concentration of approximately 80% and higher show theadvantages of the use of amido derivatives in the most noteworthymanner, the use of amides is also advantageous with acids heretoforeused as parchmentizing acids, for example, acids as low as 65% H2804 asshown in the following example. At the other end of the concentrationrange, acids of 100% strength and over, for example, 103% (thuscontaining free S03) may be employed withgood results.

Example 21 A 68/76 unfinished cotton voile fabric was' treated for 20seconds in a solution of 40 gms. urea in 800 gms. of 70% sulfuric acid.The fabric was then washed and dried by ironing. This treatment resultedin a. stiff springy finished but slightly harsh for an organdy.

Example 22 5. Cloth treated with 96% sulfuric acid tages of thisinvention are most striking. This is all the more surprising sincematerials such as formaldehyde which have hithertofore been recommendedfor use with acids of moderate concentration are ineffective with theconcentrated acid.

Voil fabrics were treated for 20 seconds each in acids of the followingcompositions and tensile strengths determined with the results noted.The tensile strength shown is the force in pounds necessary to break aone inch strip of the cloth.

Pounds 1. Untreated cloth 7.5 2. Cloth treated with solution of 20 gms.urea in 100 gms. 96% sulfuric acid 3. Cloth treated with solution of 20gms.

urea in 110 gms. of 87% sulfuric acid 9.3 4. Cloth treated with solutionof 30 gms.

urea in 105 gms. of 91% sulfuric acid 10.2 0.0

'ihis amount of urea was not completely soluble in the acid at. roomtemperature and so was not all in solution.

In addition to use in the treatment of fabrics, solutions of theseinhibitors in sulfuric acid may be used for parchmentizing paper andtreating regenerated cellulosic films, and as regeneration baths inthespinning of viscose yarn, or for subsequent treatment of viscose yarn,for example, to secure higher tenacity.

The parchmentized effects obtained by the present invention are notnecessarily superior to the effects obtained by prior art methods butthese effects can be obtained more consistently and with less spoilageof goods than is obtained by prior art processes. Thus in one of the recognized prior art processes for producing organdy finishes, there isfirst a mercerization in 20--25 per cent sodium hydroxide, followed by atreatment at a low temperature and at an inconveniently high speed, withsulfuric acid of about 66% concentration. The high speed is necessary toavoid ruining the fabric. Following the acid treatment the cloth isgiven another mercerization. On-the other hand the process of thisinvention involves in its simplest form only a single acid treatmentcarried out at room temperature, in order to produce a satisfactoryorgandy finish. Furthermore the process of the present invention allowsof a very great variation in the effects obtained, since the variousfactors such as time and temperature of treatment, and agents used canbe varied at will over rather wide limits according to the effectsdesired.

The above description and examples are intended to be illustrative only.Only modification of or variation therefrom which conforms to the spiritof the invention is intended to be included within the scope of. theclaims.

I claim: i

1. Process which comprises immersing a cotton fabric at 20 C. for 30seconds in a solution of 20 g. urea in 100 g. of 96% sulfuric acid,removing from said solution, washing with water and then with 3% ammoniasolution and drying by ironing.

2. Process which comprises treating cotton fabric with sulfuric acid ofat least 85% concentration containing 5-35 parts by weight of urea per100 parts of H2804.

3. Process which comprises treating cotton fabric with concentratedsulfuric acid of at least 65% strength containing urea.

4. Process which comprises treating cellulosic textile materials withsulfuric acid of at least 65% strength containing urea.

5. Process which comprises treating cellulosic textile materials withsulfuric acid of at least mula ,1

wherein R, R and R are hydrogen or organic radicals containing up to sixcarbon atoms, the

nitrogen content of said- 10%.

8. Process which comprises treating a cellulosic fabric with aparchmentizing reagent until a still, springy, at least partlytransparentized flnish is obtained, thereupon discontinuing thetreatment, and promptly washing out the reagent said parchmentizingreagent comprising sulfuric acid of at least 80% concentration havingdissolved therein per 100 parts acid from 5-35 parts of a cellulosedegradation inhibitor; said inhibitor comprising a low molecular weightamide which is soluble in 96% sulfuric acid at C. to the amount of atleast 20 parts per 1000f acid and which is further characterized by thefact that it reacts positively in the tendering resistance test,

amide being at least said test comprising, the step of dissolving 20'parts inhibitor in 100 parts 96% sulfuric acid,

bringing the solution to 20 0., immersing therein a sample of cottonvoile for a period of 30 seconds, thereupon removing the sample from thebath, and promptly washing out the acid and drying, a positive testbeing indicated by the fact 7 that the sample is found to beparchmentized and to have lost at least partly not more than of itsoriginal tensile strength.

9. As a treating agent for cellulosic materials,

a concentrated sulfuric acid solution of urea.

10. As a treating agent for cellulosic materials, a solution, insulfuric acid of at least 65% concentration, of urea.

11. As a treating agent for cellulosic materials a solution, in sulfuricacid of at least 85% con-,

centration, of an amido compound of the formula R-cx-N textile materialswith least 65% wherein R is hydrogen, an amino group or an alkyl group,R and R are hydrogen or hydrocarbon radicals and X is oxygen sulfur oran imino group.

12. Process which comprises treating a cellu-- textile materials withsulfuric acid of at least 65% concentration containing thiourea insolution therein.

14. Process which comprises treating cellulosic textile materials withsulfuric acid of at least 65% concentration containing in solutiontherein 5-35 parts of thiourea per 100 parts of concentrated,

sulfuric acid.

15. Process which comprises treating cellulosic sulfuric acid of atleast 65% concentration containing foramide in solution therein. 16.Process which comprises treating cellulosic textile materials withsulfuric acid of at least 65% concentration containing in solutiontherein 5-35, parts of foramide per 100 parts of concentrated sulfuricacid.

17. Process which comprises treating cellulosic textile materials withsulfuric acid of at least 65% concentration containing therein as acellulose degradation inhibitor a low molecular Weight amide soluble in96% sulfuric acid at 20 C. to the extent of at least 20 parts per 100parts of acid and having its amido group attached to a carbon atomdoubly bonded to a non-metallic member of the sixth group of theperiodic table having a molecular weight between 16 and 32.

18. Process for producing an organdy effect which comprises treating athin cellulosic fabric with sulfuric acid of at least 65% concentrationcontaining dissolved therein a low molecular weight amide.

19. Process for producing an organdy effect which comprises treating athin cotton textile material with sulfuric acid of at least 85%concentration containing in solution therein 5-35 parts by weight ofurea per 100 parts of concentrated sulfuric acid.

20. Process for producing an organdy effect which comprises treating athin cotton textile material with concentrated sulfuric acid of atstrength containing urea.

JOSEPH HARREL SHIPP.

CERTIFICATE OF CORRECTION Patent No. 2,17u,5 5u. October 19 9.

JOSEPH BARREL SHIPP.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,first column, line 65, for the word "finished" readfinish; page 6,second column, lines 28 and 55, claims 15 and 16 respectively, for"foramide" read fonnamide; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord ofthe case in the Patent Office.

Signed and sealed this 12th day of March, A. D. 19h0.

. Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

